dmaengine: bestcomm: Prepare cleanup of powerpc's asm/prom.h

powerpc's asm/prom.h brings some headers that it doesn't
need itself.

In order to clean it up, first add missing headers in
users of asm/prom.h

Signed-off-by: Christophe Leroy <[e-mail]>
Link: https://lore.kernel.org/r/f98acba3[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/bestcomm/bestcomm.c

···
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/of_device.h>
+#include <linux/of_irq.h>
 #include <linux/of_platform.h>
 #include <asm/io.h>
 #include <asm/irq.h>